Profile turning and boring lathe



INVENTOR5: Lorenz Auger Charles HJO nson fllua Aw ATTORNEYS.

l0 Sheets-Sheet l n W Q h h Illlllll lllll lll L A LEIFER ETAL PROFILE TURNING AND BORING LATHE Feb. '3, 1953 Filed June 9, 1950 Feb. 3, 1953 L. A. LEIFER ETAL 2,627,194

PROFILE TURNING AND BORING LATHE Filed June 9, 1950 10 Sheets-Sheet 2 Charles H.J0 nson %M x NAM ATTORNEYS.

Feb. 3, 1953 L. A. LEIFER ETAL PROFILE TURNING AND BORING LATHE l0 Sheets-Sheet 3 Filed June 9, 1950 Feb. \3, 1953 L. A. LEIFER ETAL 7,

PROFILE TURNING AND BORING LATHE Filed June 9, 1950 10 Sheets-Sheet 4 Z4 INVENTORS.

Lorenz A.Lezfer Charles H. Johnson %alw 61M ATTORNEYS Feb. 3, 1953 Filed June 9, 1950 L. A. LEIFER ETAL PROFILE TURNING AND BORING LATHE 10 Sheets-Sheet 5 VIII INVENTOR3. LorenzALeifer Charles HJohnson BY faiwzlwe ATTORNEYS Feb. 3, 1953 LEIFER T 2,627,194

PROFILE TURNING AND BORING LATHE Filed June 9, 1950 l0 Sheets-Sheet 6 k a: 1: II 5' I 8 I l ,ll" gn E E 76 1% 61 112 85/ 59 M41 N 77 J Lbrenz A.Leifer Charles h. Johnson A 4 U m n V v 74 7 9 1H9 INVENTORS.

ATTORNEYS Feb. 3, 1953 L. A. LEIFER ETAL 2,627,194

PROFILE TURNING AND BORING LATHE Filed June 9, 1950 10 Sheets-Sheet I I r/ V i 1 f I 44 46 l i l l um 99 INVENTORfi. Lorenz A.Leifcr Charles H.Johns0n M flklw zjm ATTORNEYS Feb. 3, 1953 L. A. LEIFER ETAL 27,

PROFILE TURNING AND BORING LATHE Filed June 9, i950 1o Sheets-Sheet 8 INVENTORS. I1 Lorenz A Leifer- Charles l-LJohnson BY fia/wr MW ATTORN EYS INVENTORS.

A.Lezfifer Charles HJa nson ATTORNEYS 10 Sheets-Sheet 9 Lorenz m w/wz L A LEIFER ETAL PROFILE TURNING AND BORING LATHE Feb. 3, 1953 Filed June 9, 1950 Patented Feb. 3, 1953 UNITED STATES PATENT OF P ICE PROFILE TURNING AND BORING LATHE Application June 9, .1950, Serial No. 167.002

"30 Claims. (Cl. 717-3) .Thisinvention relates to an automatic profile turning and boring lathe, the principal features of which have been embodied in a lathe providing :for automatic repeat-cutting operations of predetermined cutting depth andlength.

One of the principal objects of the invention is to provide a profile turning vand'boring mechanism that will automatically repeat in successive cuts of predetermined depth upon a single workpiece until the machiningof the workpiece is completed.

Anotherobject of the invention is to provide suchsuccessivetcutting operations with a single tool and'with stop indexes to determine the traverse and feedinaocordance with the individual length of each given out.

.Another object is to provide a fully automatic profile turning and boringdevice adapted to complete a series of successive cutting cycles by a single tool upon a single workpiece, and then to be automatically returned to starting iposition'for repeating the same series of cuts upon a succeeding workpiece.

Another object is to utilize a fluid pressure actuation for the clutches and power cylinders with electrical switching means for automatically controlling thesame through solenoid operated valves whereby the control is obtained more accurately and wells may be provided for completion of the machining of shoulders and the like.

Other objects and. advantages will be set forth in detail in theaccompanyingdescription of an embodimentof theinvention as incorporated in a profile boring lathe and illustrated in the accompanying drawings.

In the drawings:

Figure l is a front side elevation of the'la'the;

Fig. 2 is a top plan view of the lathe of Fig. 1;

Fig. 3 is a longitudinal section taken axially of the spindle and feed shaft in the'headstock;

Fig. 4 is a transverse vertical section taken on line 4i of Fig. 3 of theheadstock;

Fig.5 is an enlarged detail section showing the initial feed clutch mechanism for driving the feed shaft from thespindle;

Fig. 6 is a rear end'view of Fig. 2showingthe feed chain;

Fig. 7 is 'atransverse horizontal section taken on line 1-! of Fig. 6 and showing the drive clutches;

Fig. 8 is a vertical section taken axiallyof the frontslide showing the-drive therefor;

Fig. Q'isan enlarged section takenon 1ine:9-9 of =8 and showing the front slide construction;

Fig. 10 is a detail horizontal section takenon line iii-4i] of Fig. Sand showing the p'laten lock;

Fig. 11 is a detail'vertical section showing the adjustable stopfor determining the bore size;

Fig. 12 is a detail view showing the -stepoc'am and index drum actuating member;

Fig. 13 is a detail transverse section taken on line I3l3 of Fig. 12 showing the gearin'g for indexing the drum;

Fig. 14 is a detail plan view showing-the contour cam follower and itsactuation;

Fig. 15 is a schematic plan -view of the slide and cam structures inposition forinitiating the first cutting operation;

Fig. 16 is'a. view similarto Fig. 15 showing t'he parts approaching theendof the'last cutwherein the internal bore of the workpieceis'being cut;

Fig. 17 is a rear side elevation showing *the rear slide;

Fig. 18 is a schematic "plan view showing'the rear slide with itstoollin cutting position;

Fig. 19 is a schematic diagram of the several moving parts showing the actuating cylinders andvalves and'the location of the switches "employed in-controlling the severalmovements and Fig. 20 is a schematic'wiring diagram for the control of themachine.

The lathe illustrated is of a type having a bed vi, a headstock t andamovable iplaten or table 3 disposed on the bed to move'toward and away from the headstock into and out of operative position.

Thebed l is generally short andhaslongitu'dinal ways 4 upon which table 3 moves. Power cylinders? and'5 are mounted along the corresponding sides of bed I, having pistons 6 and 6', respectively, with forwardly 'extendingpist'on rods 7 and 1', respectively, for moving the table. For this purpose the rear-piston rod 1 has its forward end secured to a bracket 8 depending from the forward endoftable 3.

The forward end of the front piston rodl passes through a housing 9 bolted to theibottom of table 3 near the forward end of the latter, and has a pull head it) atthe end of the rodlfor engaging the housing .9 to assist in moving the-tablerearwardly.

Housing 9 contains the table lock mechanism which comprisesabell-crank lever H pivoted .to the housing 9, and which operates a lock pin I2 extending horizontally toward'the bed I. The inner end of lock pin I2 carries a roller l3 adapted toride along atrack I l secured to the front side of bed I. The short arm of the bell crank lever ill engagesin a notch 15 in the front pistonrod 1 whereby forward movement of the rod urges inward movement of the locking pin l2 and its roller 13 against track I4.

When table 3 reaches its forward position, roller I3 drops into a notch 16 in track l4 thereby locking housing 9 and table 3 against further forward movement. At the instance of completion of this locking action a stop collar ll secured on rod 1 engages the housing 9.

Stop collar I! has an arm 18 thereon which engages the button of a limit switch l9, as will be described more fully hereinafter.

The return movement of table 3 is effected by movement of the pistons 6 and 6 rearwardly in the corresponding cylinders 5 and 5'. The front piston rod 1 in its initial rearward movement actuates bell crank lever H to withdraw roller [3 of locking pin l2 from recess I 6 in track I 4, thereby releasing table 3 for rearward movement. Thereupon pull head 10 engages housing 9 and assists in pulling table 3 rearwardly.

The headstock 2 of the lathe has a spindle drive motor 20 mounted thereon and connected by means of multiple V-belts 2! to a main drive shaft 22 in the headstock. The drive shaft 22 is connected to drive the lathe spindle 23 in the headstock 2 by means of suitable transmission mechanism not shown.

A feed shaft 24 extends through the headstock 2 parallel to the spindle 23 and rearwardly to the opposite end of the bed, for driving the tool slides as described hereinafter.

The feed shaft-24 is driven in forward feed in correlation to the spindle speed by means of gearing 25 extending directly from the spindle 23 to a cross shaft 26 carrying a worm 2'! driving a 1'0- tary clutch member 28 rotationally mounted upon shaft 24. A second clutch member 29 is carried by shaft 24 and rotationally secured thereto. The clutch member 29 is axially movable into and out of engagement with clutch member 28 to thereby selectively drive the feed shaft 24 from the spindle 23. For this purpose a clutch actuating, rod 30 extends axially into the end of shaft 24 tothe location of the movable clutch member 29, and a transverse pin 3| extends through the rod 30 and the hub of member 29 to actuate the latter in response to longitudinal movement of the rod, as shown in Figs. 3 and 5. A longitudinally extending slot 32 is disposed in shaft 24 on opposite sides of rod 30 to receive pin 3| and provide for its movement axially of shaft 24. The clutch actuating rod 36 is pushed inward- 1y to effect engagement of clutch member 29 with clutch member 28, by means of a lever 33 pivotally mounted on the wall of headstock 2 and having one end engaging the outer end of rod 3. The opposite end of lever 33 is engaged by the outer end of a piston rod 34 of piston 35 operating in air cylinder 36.

The clutch members 28 and 29 are normally biased apart by suitable springs 31 and push rods 38 actuated thereby in the body of clutch member' 28 (see Fig.5). If desired, an additional spring 39 may be employed at, the inner end of rod 30 to bias the same outwardly.

The shaft 24is driven at traverse speeds for both forward and back traverse of the slides, by a traverse motor 40 mounted at the rear of headstock 2, and the shaft of which is connected to shaft 24 by drive chain 4| and suitable sprockets.

The table 3 carries at least one tool slide, the table shown having a front tool slide 42 and a rear tool slide 43. The slides 42 and 43 are mounted upon corresponding ways 44 and 45 which are preferably adjustably bolted to table 4 3 in selected angular position relative to the axis of spindle 23. In the construction shown, front slide 42 has its way 44 secured to obtain a slide movement parallel to the axis of spindle 23 for boring operations. Rear slide 43 has its ways 45 secured at an angle to the axis of spindle 23 for corner chamfering of the workpiece 46.

The workpiece 46 in the present instanc is illustrated as a cylindrical forged blank for the construction of an oil well tool joint. The blank 46 is secured in a chuck 41 carried by spindle 23. The chuck 4'! is actuated by a suitable air cylinder, not shown, through the hollow spindle 23, as is customary with lathes.

The tool slides, 42 and 43 are traversed in both directions and fed forwardly by means of feed shaft 24. For this purpose a chain 48 connects shaft 24 at its rear end with a corresponding shaft 49 for each slide, by means of suitable sprockets on the respective shafts.

Each shaft 49 is mounted on table 3 and car ries an axially movable clutch member 50 rotatably secured thereon and which is adapted to be moved axially into and out of engagement with a corresponding clutch member 5| on a stub shaft 52 carried by table 3 (see Fig. '7). Stub shaft 52 is connected by a universal joint 53 to a couplin shaft 54 which in turn is connected at its opposite end by a universal joint 55 to a shaft 56 in the base for the corresponding ways 44 or 45.

Shaft 56 for each slide is geared to drive a cam drum 57 disposed centrally of the corresponding ways 44 or 45 and parallel to the direction of travel of the corresponding slide 42 or 43. Each drum 57 has a spiral cam groove 56 in its outer surface into which a cam follower 59 depends from the corresponding tool slide so that as the drum is rotated the cam follower 59 is moved axially along the drum to move the slide accordingly.

The movable clutch members 59 are separately actuated by a lever 66 pivoted at one end to clutch housing 6! and having a shift pin 62 riding in a circumferential groove 53 in the hub of each corresponding clutch member. The outer end of lever 69 for the front slide is moved by a pair of opposed electro-magnetic solenoids 64 and 65 mounted on clutch housing 6i on table 3 and having their plungers hinged together at the center and flanged to provide a recess for receiving the end of the lever and actuating the same in accordance with movement of the plungers. Opposed solenoids 66 and 61 are similarly provided on the corresponding clutch housing on table 3 for actuating the lever 66 for the rear slide clutch.

In the construction illustrated, as the solenoids 64 and 66 pull their respective clutch levers 66 toward the same, clutch members 56 are moved into engagement with the corresponding clutch members 5i, and as the solenoids 55 and 6'! pull their respective clutch levers 66 toward the same, clutch members 56 are disengagedfrom the corresponding clutch members 5i. By employing a clutch 565i for each of the tool slides 42 and 43 the slides may be actuated selectively 0r simultaneously, as may be desired.

In the machining of the workpiece 46, illustrated, it is desirable to first effect the internal boring operations by the front slide 42 and then to effect the corner chamfering by the rear slide 43. In carrying out the machining operations described, it becomes necessary to employ repeat games outs for the internal boring'operations since the depth of cut necessary toprovide thetaper bore profile desired is-too great for a single cut operation.

The lathe of the present-inventionis adapted to effect the desired taperboring operations in successive cuts of predetermined individual depths, then to bore the inner section of the blank, and then to cornerchamfer the end of the blank, all automatically in a single cycle of operation of the lathe.

In general, the above is accomplished by mounting the boring toolES upon a cross slide 69 on frontslide .42 and "changing the position of'the cross slide 69 toeffect the desired adjustment for the depth of cut for each successive cutting. operation. This latter is accomplished by employin a contour "camlll for controlling the movement of the cross slide '69 during feeding of slide 42 to effect the desired contour cut, and then changing the position of cam it between each successive cut to effectthe desired re-setting of the tool Bil to provide the desired depth of cut therefor.

The position of contourcam it is adjusted by means of a step cam." which'is indexed with the out as described hereinafter. Since thelength of the several cuts will vary, the length of feed for slide dais determined by a control and stop drum E2 which isindexed simultaneously with the step cam 1 I- The mounting and operation of the contour cam, step cam and control drum may vary in different lathes and .to suit different machining operations. The several cams may be constructed to provide different contours of cut and for different numbers of successive cuts.

Inthe lathe illustrated, the contour cam i9 is shaped to simulate the internaltaper bore contour desired in the exposed end of workpiece 66. The cam iii is mounted on slide plate it! carried in a housing is on table 3. Plate 13 is supported upon a second similar plate 15 in housing M, and both plates 13 and there disposed for adjustment .in a direction normal to the direction of feed of slide 42 and generally parallel to the direction of movement forcross-slide 69.

Plate 13 maybe adjusted in its position relaive to plate 75 by means of a micrometer screw 16 carried by a bracket ii on the outer end of plate 13 and threaded into the outer end of plate '15 to provide a fine adjustment for the final cut of .tool 68.

The position of plate 55, and with it that of plate l3and contour cam 19, is adjusted bysteg cam ll which is disposed beneath and to the rear of the platesand is engaged on its front step cam surface '13 by a roller '59 on a stud 8! depending from lower plate H5.

The step cam H is disposed in a transverse groove in housing M on table 3 and is disposed to be indexed a predetermined longitudinal movement for each successive cutting operation. In each indexing movement of step earn it an additional step is presented to move rollertl'S and with it'plates i3 and 15, contour cam '58 and cross-slide 69 in the direction of the necessary depth adjustment for cutting tool 68.

The position of cross-slide 69 is governed'by contour cam ill by means of a cam follower 8! carried by the cross.slide.and adapted to engage the front cam surfaceofithe contour cam and to ridealongthe same as slide 42 feedsforward. The length of the cam surface of .contour cam should beat least as-great'as thetotdl'length of the contour cut-so that thefollower-Bl controls the cutthroughout the feeding movement therefor.

In the final cut for-the workpiece 46 illustrated, it is desirable to have tool 68 continue andbore the central cylindrical portion of the'blank after completing the contour out. For this purpose the inwardmovement of cross-slide 89 is stopped at a predeterminedposition to eflectthe desired diameter for the internal bore, by employing a threaded stop 82 carried by the frontof the cross-slide'ancl extending inwardly therefrom to engagethefront of a portion of the slide 42. The stop 82 is-adjustable by means of a micrometer screw indicator 83 at its forward end,

Upon the back traverse of slide 42 in each'instance it is desirable to remove boring tool6'B from the work, and this is'accomplished by mounting cam follower s! toextend inwardlyon arotatable vertical shaft as whereby rotation of the shaft approximately 60 will effect a release of the follower from contour cam in and permitcross-slide 69 to move in a direction spacing thetool 68 from the work.

The cross-slide Sills biased inwardly at all times to provide a substantially constant pressure of 01- lower 3! against cam Iii, by suitable ineanssuch as a hydraulic cylinder or the compression spring 85 disposed in a channel in slide 42 and bearing against an abutment of slide 69. If need be, the force of the compression spring 35 may be:'sup plemented during machining operationsby'an air cylinder as and piston 81 mountedbetween crossslide 59 and slide as.

The shaft Se is journaled in a bearing support'flll at the front end of cross-slide 69 and the upper end of the shaft carries a crank .89 which is operatively pivotally connected to the outer end of a piston rod having its piston 91 operating in an air cylinder 92 having its opposite endpivotally supported by a bracket 93 on cross-slide B9.

The step cam TI is indexed automatically for successive cuts of the boring tool =63 by the back traverse movement of slide 42. For this purpose a shank extension of step cam II has a number of ratchet notches 94 in the rear .side thereof corresponding to one less than the maximum number of cuts to be taken.

The notches 94 are arranged in series relation and are disposed in relative spacedrelation corresponding to the spacing of the cam steps in cam surface E8. In the initial positioning of cam strip H at the start of the cycle and with roller 19 engaging the first control region of cam surface 18, all but the first notch 94 are disposed in the groove confining cam strip TI. The back of the groove referred to consists of an upright plate 95 against which the cam strip H abuts and which hides the unexposed notches M.

A pawl 95 is pivoted to the front of slide 42 on a vertical pin 9? andextends toward headstock 2 to have its head 93 move along a path adjacent the ratchet notches 9 3 during movement of slide 432. The pawl is biased toward ratchet notches 94 by spring 99 disposed betweenthe pawl and slide 42.

During initial forward movement of slide 42 the pawl es cams over the first open notch 8411f the ratchet and over plate 95 covering the remaining ratchet notches 9%. Thereafter, during back traverse of slide 32 the pawl 96 rides along plate 95 and then passes into the exposed notch 96 and draws cam strip Tl along with it to the end of theback traverse .jforslide J12, which is a distance sufficientto justexposethe next succeeding notch 94" from behind plate 95 and present the first step of cam surf-ace 18 beneath roller 19. Upon the next succeeding forward movement of slide 42 pawl 96 cams out of its notch 94 and over plate 95 and is ready for the next indexing movement upon back traverse of the slide 42.

p The successive operations of slide 42 are controlled by the drum 12 having a plurality of similar control faces I thereon corresponding in number to the maximum number of cuts employed for tool 68. Drum 12 is adapted to be indexed to present a corresponding control face I30 for each successive cut.

For this purpose the shank extension of step cam strip 1| has a gear rack IOI diagonally disposed on the upper front corner thereof. A gear I02 meshes with rack I0! and is secured to rotate a diagonally disposed shaft I 03 having a beveled gear I04 at its upper end meshing with a-bevel gear I 95 on the end of drum 12. The gear ratios are such that each indexing movement of cam M will effect a corresponding indexing movement of drum 12 to present the next successive face I00 in operative position.

Each face I00 has two or more control dogs I06 and I01 thereon. Dog I06 is disposed to be engaged by the operating lever of a switch I08 when slide 42 reaches the position in its forward traverse where feeding should commence, whereupon switch I08 effects the desired controls as described hereinafter. Dog I01 is disposed to be engaged by the operating lever of a switch It!) when slide 42 reaches the position in its forward feed where it is desired to stop the feed and back traverse. The back traverse continues until the rear end of slide 42 engages and trips a switch I I0 mounted on a bracket I I I on the corresponding clutch housing GI on table 3 and thereupon switch I I0 stops the back traverse.

The drum 12 carries a dog II2 which is positioned to engage the operating arm II3 of a switch I I4 when the drum is indexed for the last cutting operation and thereby shift the next operation to the rear slide 43 upon actuation of switch IIO by the final back traverse of slide 42.

The rear slide 43 then traverses forward until a cam II5 thereon actuates a switch II6 on the base of way 45, and shifts the slide from traverse to feed. During feeding of rear slide 43 the corner chamfering of the end of workpiece 45 is accomplished by tool II1 carried by the slide.

At the end of the feed stroke for slide 43 a stop rod II8 on the side of the slide actuates a switch II9 on the base of way 45, which then initiates the back movement of table 3 withdrawing all tools from the proximity of the work and restoring switch I9 to normal.

Restoration of switch I9 to normal effects back traverse of rear slide 43 until a bracket stop on the rear end of the latter engages and trips switch I20 on the base of way 45, whereupon back traverse is stopped and all parts are restored to initial position for starting a new work cycle.

The restoration of the parts to normal includes a recocking of the step cam H and control drum 12 to starting position. This is accomplished by an oil cylinder I2I on table 3 having a piston I22 with its piston rod I23 connected to the shank extension of step cam 1I whereby upon application of pressure oil to the piston I22, through valve I24 from a small pump I25 on headstock 2, the piston pushes step cam 'II toward the headstock 2 to starting position. At the same time gear rack II on cam strip -1I returns drum 12 to start position for another work cycle.

The above description of the operating cycle can be more readily understood by reference to the diagrams of Figs. 19 and 20.

Referring to the wiring diagram in Fig. 20, the several switches are shown in their normal position after closing of the main line circuit breaker switch I28 and turning of the chuck-unchuck switch I21 to position for chucking of a workpiece 49 at the start of a cycle. The main line supplies current to the spindle motor 20 through a normally open switch I28 and to traverse motor 40 through normally open forward and reverse switches I29 and I30 respectively, and to the control switches, relays and solenoids through a transformer I3I.

The switch I21 referred to opens a circuit from the secondary of transformer I3I through a solenoid I32, serving to shift a two-way valve I33 in the air pressure branch line I34 leading to the double acting chuck actuating cylinder I35, shown schematically in Fig. 19, to effect closing of the chuck 41 upon the workpiece 46.

The cycle is then started by the operator pressing the start button I39 which closes the normally open starting switch I 31 and thereby completes a circuit from the secondary of transformer I 3| through the normally closed stop switch I 38, the closed unchuck safety cut-out switch I39, switch I31, and the platen solenoid I 40 which op erates valve MI in air branch line I42 leading to the rear ends of the platen cylinders 5 and 5', resulting in a forward feed of the platen or table 3. At the same time the circuit is closed by start switch I31 through normally closed switch H9 and a time delay relay I43 which closes the holding contacts I44 by-passing starting switch I31 so that the start button I36 may be released by the operator.

Relay I 43, when energized, also opens an interlock switch I45 to prevent energization of the rear slide clutch engage solenoid 66. Energizing of relay I43 also closes a switch contact I46 which completes a circuit from the secondary of transformer I3I through a normally closed contactor I41, slide sequence selector switch I48 and the front slide relay coil I49.

Relay I49 closes a switch I50 to complete a circuit from the secondary of transformer I3I through the clutch engage solenoid 64 for the front slide 42 and also closes a switch I 5I to complete a circuit from the secondary of transformer I3I through the clutch disengage solenoid 61 for the rear slide 43. Thereupon clutch 50-5I for the front slide is closed and clutch 505I for the rear slide is held open.

As table 3 moves forwardly a limit switch I 52 disposed on the rear side of bed I is shifted by a cam I53 on the underside of the table to complete a circuit from the secondary of transformer I3I through stop switch I38, interlock I39 and either start switch I31 or holding switch I44, and through the solenoid I54 employed to close the spindle switch contacts I28 to energize spindle motor 20, thereby starting the spindle 23 to rotate. Solenoid I54 stays energized throughout the remainder of the cycle.

Prior to this shifting of switch I52 and at the time start button I36 was originally actuated, a circuit was completed through the start switch I31 and a solenoid I55 which opens valve I24 and actuates cylinder I2I to recock the step cam H and drum 12 to start position.

As table 3 reaches the. end of its forward movecuit as described hereinafter.

ment where lockiroller I3 on pin 12 enters lock notch I6 in track I4, the arm I8 on stop collar I1 engages switch I9 and shifts the same to complete a circuit from the secondary of transformer I3I through switch I9, the normally closed switch II 0, a normally closed switch I56 and the forward traverse relay I51, which latter then closes switch I50 and thereby completes a circuit from the secondary of transformer I3I through the forward traverse solenoid I59 which is then energized to close the forward traverse switch contacts I29 and energize traverse motor 49 in a forward direction.

When slide 42 starts to traverse forwardly, it moves away from limit switch IIO thereby permitting this switch to shift to back traverse position ready for closing of the back traverse cir- Energization of forward traverse relay I51 continues by a holding circuit through switch I13, switch I08, normally closed contacts I 69,.holding contactor I6I closed by relay I51, and the normally closed contacts Traverse motor 40 thereupon drives feed shaft 24 by chain 4|, and feed shaft 24 drives the front slide 42 in forward traverse until a dog I06 on the corresponding first face of drum 12 trips switch I08.

When switch I08 is shifted by dog I06 it opens the circuit for forward traverse relay I51, thereby terminating energization of the traverse motor 40 by ale-energizing solenoid I29 and opening switch I59, and it completes a circuit from the secondary of transformer I3I through switch I9, switch I08, the contacts I63, held closed by.

relay I43, and the feed solenoid I64 which closes valve I65 in branch air line I66 leading to cylinder 38, the piston 35 of which actuates feed clutch 28-49 to close the same and effect forward feed of front slide 42. At the same time a similar cir-.

cuit is completed through tool relief solenoid I61 to energize the same and open a valve I68 in a branch air line I69 leading to the front end of cylinder 92 to turn shaft 84 and cam follower 8I so that the latter properly engages the con tour cam throughout the feeding operation.

Shifting of switch I08 as described also completes a circuit from the secondary of transformer I3I through switch I9, switch I08 and time delay relay I19 which in turn closes a holding switch. III in a circuit for the feed solenoid face of drum 12 engages the actuating arm of switch I09 which then opens the circuit of feed solenoid I84, stopping the feed, and also opens the circuit of time delay relay I10, thereby opening switch Ill and closing contacts I60. The time delay relay I10 is set to delay the closing of normally closed switch contacts I12 in a back traverse circuit sufiiciently long to allow the tool 68 to clean up the cut circumferentially of the workpiece, and thereupon the back traverse control circuit is completed from the secondary of transformer I3I through switch I9, switch I09, switch I12 and back traverse relay I13.

Energization of relay I13 completes a holding circuit for itself through switch I9, switch IIO At the same time relay and normally open holding contacts I14. Relay I13 also closes switch contacts I15, thereby completin'g a circuit from the secondary of transformer I3I through contacts I80 and the back traverse solenoid I16 which closes the back traverse switches I leading. to motor to energize the latter in reverse, thereby effecting the back traverse of front slide 42.

During the back traverse of slide 42 switch I09 returns to normal starting position. Likewise pawl 96 willengage the first notch 94 toretract step cam I! one step to the right so thatthe step cam. 1| is indexed to adjust the depth of the next succeeding cut of tool 68, and drum 12 is indexed to present the next successive set of dogs for controlling the" traverse and feed of slide 42.

Also during the back traverse the cam follower 8| turns on cam 10 to relieve the tool 68 from the work' 46. For this purpose solenoid I61 is automatically de-energized alongwith feed solenoid I64 to reverse the valve I68 leading to cylinder 92' and thereby turn the shaft and cam follower 8 I.

When slide 42 reaches its retracted position it engages switch H0 and shifts the same to open the holding circuit for back traverse relay I13, and to close the initial forward traverse circuit for forward traverse relay I51 to starta second cutting operation which then proceeds exactly as described above for the first cutting operation. During back traverse from the second cut the pawl 96 will catch in the second notch 94 and thereby index step cam H and drum 12 for the third cutting operation. A notch 94 is provided for indexing step cam 1| for each successive cut. 7

The cutting operations for tool 68 are thus repeated until the final cut is complete. Upon the indexing of drum 12 for the final cut, dog I I2 closes the normally openswitch I I4 and thereby completes. a circuit from the secondary of transformer I3I through switch I9, switch H4 and a time delay relay Ill. The time lag of this relay I11 is such that it does not function until after the forward traverse of slide 42 releases switch I I0 so that the latter shifts to back traverse position and forward traverse of the slide is continued through the holding circuit described previously.

Relay I11 serves to shift switch I56 to open position so that forward traverse of slide 42 will not be initiated when switch H0 is engaged upon the. next back traverse of the slide. At

. the same time relay I11 closes a normally open switch I18 preparatory to the operation of the rear slide 43 upon engagementof switch H0 as the back traverse of slide 42 is completed. For this purpose shifting of switch IIO by the back traverse of slide 42, as before,.opens the holding circuit for the backtraverse relay I13 thereby stopping slide 42 in its retraced position, and completes a circuit from thesecondary by transformer I3I through switch I9, switch II0, switch I18 and the rear slide relay coil I19.

Energization of relay I19 opens then'ormally closed contacts I41 to thereby de-energize the frontslide relay coil I49 and return its switches I50 and I5I to normal open position therebydeenergizing clutch solenoids 64'and 61. Th'erelay I19 also shifts the slide clutches 50-5I by closing" switch I to complete a circuit from the secondary of transformer I3I through the solenoid 69 forrear slide 43 thereby closing: the rear slide clutch 50-5I, andby closing. switch I and the secondary of transformer I3I.

attain .I8I to complete a circuit from the secondary of .transformer I3I through solenoid 55 for the front forward traverse relay coil I51, thereby effecting forward traverse of the rear slide 43.

Forward traverse of rear slide 43 continues until cam II 5 actuates switch H6 to thereby open the forward traverse circuit just described and complete a circuit to the feed solenoid I64 and to time delay relay I through switch I48,

: switch I9, contacts I (ill and I82 and the secondary of transformer I3I.' Energization of relay I10 closes the holding contacts I1I permitting switch I I 6 to return to normal. 'I'hereupon the rear slide 43 is fed forward during cutting of its tool II1 until the stop rod II8 on slide 43 engages switch I I9 and opens the same.

Opening of switch II9 opens the circuit for time delay relay I43 and thereby returns its switch contacts I44, I46 and I 63 to normal open position and contacts I45 to normal closed position. Opening of contacts I44 is delayed suincient to clean up the cut by tool II1 before the 1 spindle solenoid I54 is re-energized and switch I28 is opened to stop the spindle motor 20 and de-energize solenoid I 55.

The platen forward solenoid I40 is ale-energized by the opening of switch I44 and its valve I 4! is reversed to admit fluid into the forward ends of cylinders 5 and 5. The piston 6 of front cylinder 5 then withdraws lock roller I3 from lock recess I6 in track I 4, and pull head Ill engages housing 9 to assist the rear cylinder 5 in vwithdrawing platen 3 from operative position.

As platen 3 moves rearwardly switch I9 is released and returns to normal position.

Closing of contacts I45 completes a circuit from the secondary of transformer I3I through the rear slide clutch engage solenoid 66 to retain the clutch closed for back traverse.

Opening of contacts I 43 prevents energization of the front slide contactor relay coil I49 until the next cycle of the lathe. Opening of contacts I63 stops the feed of the rear slide 43 by deenergizing feed solenoid I 64.

De-energization of relay I13 by opening of switch I9 upon the platen 3 starting back, returns switch contacts I60, Ill and I12 to normal thereby closing the circuit for back traverse relay I13 through contacts I12, switch I20, which has been closed by the forward movement of the rear slide away from the same, switch I9 Relay and energizes the back I30 to I13 closes switch I15 traverse solenoid I16 closing switch motor 40.

The rear slide thereupon back traverses until it engages switch I20 and opens the circuit just described.

drum 12 upon starting of the next cycle.

The cycle is thereupon complete and all controls are restored to normal preparatory to th 7 start of another cycle.

A slide simultaneous and sequence selector knob .I83 is shown for operating switch I48 in the, circuit of the front slide control relay I49, and a similar switch I84 in thecircuit ofthe rear slide control relay I19. Switches I48 and I84 are retained closed to provide sequence operation of the slides 42 and IE/as described. If it is desired to have the slides operate simultaneously, the control knob I83 is turned to open switches I48 and I84 and to close switches I85 and I86, respectively, for closing the circuits of the corresponding solenoids 64 and GB for engaging both clutches 5Il--5I simultaneously and at all times.

It will be understood that a spindle brake circuit, suitable manual inching and additional selector circuits will normally be added as desired.

The invention has been described in connection with a specific type of lathe and with stop boring of a workpiece. It will be understood that it may be employed with other types of lathes and for turnin or boring operations of any nature where in it is desired to take successive cuts over the same surface. The invention provides an automatic setting for the depth of cut of a turning or boring tool for successive cuts.

The invention may have various embodiments within the scope of the accompanying claims.

We claim:

1. A lathe comprising a headstock having .a rotary work spindle, a bed disposed to support a tool slide for movement toward and'away from the work carried by said spindle, a slide mounted on said bed for movement toward and away from the work, means to drive said spindle, means to move said slide in forward traverse and feedand in back traverse, a cross slide carried by said first slide for movement thereon in a direction generally normal to the movement of said first slide, a cutting tool carried by said cross slide for en gaging the work, a normally stationary step cam abutment carried by the bed and fixed in relation to the path of movement of said first slide adapted to be indexed longitudinally. for successive cutting operations with the steps thereof of a height to determine the depth of cut for each corresponding cut, means to bias said cross slide against a single step of said step cam to determine the position of cut for said tool, and automatic means to index said step cam to present successive step abutments for said cross slide to set the cutting tool for a predetermined depth of cut for each successive forward feed of said first slide.

2. A lathe comprising a headstock having a rotary work spindle, a bed disposed to support a tool slide for movement toward and away from the work carried by said spindle, a slide mounted on said bed for movement toward and away from the work, means to drive said spindle, means to move said slide in forward traverse and feed and in back traverse, a cross-slide carried by said first slide for movement thereon in a direction generally normal to the movement of said first slide, a cutting tool carried by said cross-slide for engaging the work, a normally stationary step cam abutment carried by the bed and fixed in relation to the path of movement of said first slide adapted to be indexed longitudinally for successive cutting operations with the steps thereof of a height to determine the depth of cut for each corresponding cut, means to bias said cross-slide against a single step of said step cam to determine the position of cut for said tool, means to index said step cam to present successive step abutments for said cross-slide to set the cutting tool for a predetermined depth of cut for each successive forward feed of said first slide, and automatic means operable upon the back traverse of said first slide to actuate said indexing means.

3; A lathe: comprising" a; headstock: having: a rotary workspindle, a bed disposed'to. supportta tool slide for movement toward and away from the work carried by said spindle, aslide: mounted on said bed for movement toward andv away from the work, means to drive said spindle, means to move saidslide inforward traverse and feed and in back traverse, a cross-slide carried by said first slide for movement thereon in a direction generally normal to the movement of said first'slide, a cuttingtoolcarried'by said cross-slide for engaging the-work, a normallystationarystep cam abutment carriedby the bed and fixed in relation to the path of movement of said first slide adapted to be indexed longitudinally for'successive cutting operations with the steps thereof of a height to determine the depth of cut for-each corresponding cut, means tobias said cross-slide against a single step of said step cam to determine the position of cut for said tool, means to index said step cam to present successive step abutments for said cross-slide to set the cutting tool for a predetermined depth of cut for each successive forward feed of said first slide, and a pawl and ratchet connection between said index means and said first slide to efiect actuation of said index means in response to theback traverse of said first slide.

4'. In a lathe adapted for repeat cutting operations on-a single workpiece, a main tool slide, a support for said slide, a cross-slide mounted on said main slide and carrying a cutting tool, an

abutment on said support facing in a direction corresponding to the direction of movement of said cross-slide, in moving the tool toward the" work, an abutment on said cross-slide facing said first namedabutment, means biasing said crossslide relative to said main slide in a direction eifecting engagement of said abutments, and means disposed to move one of' said abutments relative to its, support in a direction effecting a depth of cut adjustment for said tool for'each individual successive cutting operation.

5.,The lathe of claim 4 in which one of said abutments constitutes a contour cam along which the other abutment is disposed to ride during forward feeding of said first slide to effect contour cutting operations.

6. The lathe of claim 4 in which said last named meanscomprises a step cam having steps disposed to be indexed for the successive cutting operations, and an abutment disposed to engage a single step of said cam at a time and to engage successive steps of said cam in selected indexing of;the same, said cam and, last'named abutment serving to support'one of said first named abutments against'the other.

7. The lathe of claim 4 in which one of said abutments constitutes a contour cam along which the other abutment is disposed toride during forward feeding of said first slide to effect contour cutting operations, and said last named means comprises a step cam having steps disposed to be indexed for thesuccessive cutting operations, and an abutment disposed to engage a single step of said cam at a time and to engage successive steps of said cam in selected indexing ofthe same, said cam and last named abutment serving'to support one of said first named abutments against the other;

8; In a lathe adapted for repeat cutting operations on a single workpiece, a main tool slide, a supportfor said slide, a cross-slide mounted on said main slide and. carrying a cutting tool, an

abutment onzsaid' support'facing in a direction corresponding: to the: direction: of: movement:- of said cross-slide in moving the. toolttoward the work; an abutment onsaidcross -slide facing'said firstnamed abutment, means'biasing'said crossslide relative to" said main slide in a direction effectingengagement of said abutments, means disposed to moveone" of said abutments relative to its support in a direction effecting a depth of cut adjustment for said tool for each. individual successive. cutting operation, and means disposed to move one of said abutments relative to its support and to the other abutment to effect a tool relief durin back traverse of the main slide.

9'. In a latheadapted for repeat cutting operations on a single workpiece, a main tool slide, a support for" said slide, a cross-slide mounted on said main slide and carrying a cutting tool, an abutment on said support facing in a direc tion corresponding to the direction of movement of said cross-slidein moving'the tool toward the Work, an abutment on said cross-slidefacingsaid first'named abutment, means biasing said crossslide relative to said main slide in a direction effecting engagement of said abutments, a step cam having steps disposed to be indexed. for the successive cutting operations, an abutment disposed. to engage a single step of said cam at a time and to engage successive steps of said cam in selected indexing of the same, said cam and last named abutment serving to support one of said first named abutments against the other, and means operable in correlation to the back traverse of said main slide to effect indexing of said step cam and last named abutment to adjust the position of the tool and determine the depth of cut thereof during each succeeding forward feed of the main slide and tool.

10. In a lathe adapted for repeat cutting operations on a single workpiece, a main tool slide adapted to traverse and feed the tool for each cutting operation, a cross-slide mounted upon said main slide and carrying the tool for adjusting its position to determine the depth of out thereof for each successive cutting operation, indexible abutment means disposed between said cross slide and the main slide support to effect the adjustment of said cross-slide between successive feeding operations and automatically in correlation to the movements of said main slide, and means biasing said cross-slide in a direction eifecting engagement between said abutment means.

11. In a lathe adapted for repeat contour cutting operations on a single workpiece, a main tool slide adapted to transverse and feed the tool for successive cutting operations; a crossslidemounted'upon said main slide and carrying the tool therefor, two pairs of superimposed abutments disposed to control the position of said cross-slide relative to said main slide, means biasing said cross-slide relative to said main slide in a direction effecting engagement between the abutments of both pairs of abutments, one abutment of one pair of abutments constituting an indexible step cam with the successive steps thereof of a height determining the corresponding depths of cut for the tool' for the successive cutting operations, one abutment of the other pair of abutments constituting a contour cam along which its related abutment rides duringiorward feed of said main slide, andautomatic means to index said indexible abutment relative to its related abutment in correlation to the movement of said main slide-to'setthe tool for a predetermined new depth of cut for each forward feed thereof.

12. In a lathe adapted for repeat contour cutting operations on a single workpiece, a main tool slide adapted to traverse and feed the tool for successive cutting operations, a cross-slide mounted upon said main slide and carrying the tool therefor, two pairs of superimposed abutments disposed to control the position of said cross-slide relative to said mainslide, means biasing said cross-slide relative to said main slide in a direction effecting engagement between the abutments of both pairs of abutments, one abutment of one pair of abutments constituting an indexible step cam with the successive steps thereof of a height determining the corresponding depths of cut for the tool for the successive cutting operations, one abutment of the other pair of abutments constituting a contour cam along which its related abutment rides during forward feed of said main slide, automatic means to index said indexible abutment relative to its related abutment in correlation to the movement of said main slide to set the tool for a predetermined new depth of cut for each forward feed thereof, and means to relieve said contour cam abutments during back traverse of said main slide to provide a relief for the tool from the work.

13. In a lathe adapted for repeat cutting operations on a single workpiece, a main tool slide adapted to traverse and feed the tool for each cutting operation, a cross-slide mounted upon said main slide and carrying the tool for adjusting its position to determine the depth of cut thereof for each successive cutting operation,

1 a pair of abutments disposed to control the position of said cross-slide relative to said main slide, means biasing said cross-slide relative to said main slide in a direction effecting engagement of said abutments, one of said abutments constituting an indexible step cam with the successive steps thereof of a height determining the successive depths of cut for the tool in successive cutting operations, and automatic means to index said step cam abutment relative to its related abutment in correlation to the movement of said main slide to set the tool for a predetermined new depth of cut for each forward feed thereof.

14. In a lathe adapted for repeat cutting operations on a single workpiece, a main tool slide adapted to traverse and feed the tool for each cutting operation, a cross-slide mounted upon said main slide and carrying the tool for adjusting its position to determine the depth of cut thereof for each successive cutting operation, a pair of abutments disposed to control the position of said cross-slide relative to said main slide, means biasing said cross-slide relative to said main slide in a direction effecting engagement of said abutments, one of said abutments constituting an indexible step cam with the successive steps thereof of a height determining the successive depths of cut for the tool in successive cutting operations, automatic means to index said steps cam abutment relative to its related abutment in correlation to the movement of said main slide to set the tool for a predetermined new depth of cut for each forward feed thereof, and automatic means to return said step cam to starting position upon completion of the final cutting operation.

15. In a lathe adapted for repeat cutting operations on a single workpiece, a main tool slide adapted to traverse and feed the tool for each cutting operation, a cross-slide mounted upon said main slide and carrying the tool for adjusting its position to determine the depth of cut thereof for each successive cutting operation, a pair of abutments disposed to control the position of said cross-slide relative to said main slide, means biasing said cross-slide relative to said main slide in a direction eifecting engagement of said abutments, one of said abutments constituting an indexible step cam with the successive steps thereof of a height determining the successive depths of cut for the tool in successive cutting operations, means to index said step cam abutment relative to its related abutment in correlation to the movement of said main slide to set the tool for a predetermined new depth of cut for each forward feed thereof, an index drum having dogs thereon disposed to determine the successive traverse and feed movements for said main slide, and means to index said drum simultaneously with said step cam abutment.

16. In a lathe adapted for repeat cutting operations on a single workpiece, a main tool slide adapted to traverse and feed the tool for each cutting operation, a cross-slide mounted upon said main slide and carrying the tool for adjusting its position to determine the depth of cut thereof for each successive cutting operation, a pair of abutments disposed to control the position of said cross-slide relative to said main slide, means biasing said cross-slide relative to said main slide in a direction effecting engagement of said abutments, one of said abutments constituting an indexible step cam with the successive steps thereof of a height determining the successive depths of cut for the tool in successive cutting operations, means to index said step cam abutment relative to its related abutment in correlation to the movement of said main slide to set the tool for a predetermined new depth of cut for each forward feed thereof, an index drum having dogs thereon disposed to determine the successive traverse and feed movements for said main slide, means to index said drum simultaneously with said step cam abutment, and means to return said step cam and drum to starting position upon completion of the final cutting operation.

17. In a lathe adapted for repeat cutting operations on a single workpiece, a main toolslide adapted to traverse and feed the tool for each cutting operation, a cross-slide mounted upon said main slide and carrying the tool for adjusting its position to determine the depth of cut thereof for each successive cutting operation, a pair of abutments disposed to control the position of said cross-slide relative to said main slide, means biasing said cross-slide relative to saidmain slide in a direction effecting engagement of said abutments, one of said abutments constituting a contour cam along which its related abutment rides during forward feed of said main slide, and means to relieve said abutments during back traverse of said main slide to provide a relief for the tool from the work.

18. In a lathe, a main tool slide, a support for said slide, a cross-slide mounted on said main slide and carrying the tool, an abutment on said support facing in a direction of movement of said cross-slide in moving the tool toward the work, an abutment on said cross-slide facing said first named abutment, one of said abutments constituting a contour cam for governing themovement of the tool relative to the work during forward feeding movement of said slide, means to traverse and feed said main slide, and means biasing saidcross-slide relative to said main slide in a direction effecting engagement of said abutments whereby said contour cam is followed by the related abutment during feeding of the main slide.

19. In a lathe, a main tool slide, a support for said slide, a cross-slide mounted on said main slide and carrying the tool, an abutment on said support facing in a direction of movement of said cross-slide in moving the tool toward the work, an abutment on said cross-slide facing said first named abutment, one of said abutments constituting a contour cam for governing the movement of the tool relative to the Work during forward feeding movement of said main slide, means to traverse and feed said main slide, means biasing said cross-slide relative to said main slide in a direction effecting engagement of said abutments whereby said contour cam is followed by the related abutment during feeding of the main slide, said follower abutment being eccentric to a supporting axis therefor, and means to rotate said follower abutment upon the supporting axis therefor between two positions, one effecting a position of said =cross-slide during back traverse of said main slide relieving the tool from the work and the other maintaining the follower section of said abutment in contact with said contour cam during forward feed of said main slide and tool.

20. In a lathe of the class described, a main tool slide adapted to traverse and feed the cutting tool, a support for said slide, a cross-slide mount ed on said main slide and carrying the cutting tool, a contour cam carried by said support and disposed adjacent the path of movement of said main slide, a follower abutment on said crossslide adapted to ride in engagement with said contour cam during forward feed of said main slide to control the contour cutting movement of the tool, means biasing said cross-slide in a direction effecting control engagement of said follower abutment with said contour cam, and a stop abutment between said cross-slide and said main slide to limit the movement of said crossslide in response to said biasing means upon disengagement of said follower abutment and cam.

21. In a lathe of the class described, a main tool slide adapted to traverse and feed the cutting tool, a support for said slide, a crossslide mounted on said main slide and carrying the cutting tool, a contour cam carried by said support and disposed adjacent the path of movement of said main slide, a follower abutment on said crossslide adapted to ride in engagement with said contour cam during forward feed of said main slide to control the contour cutting movement of the tool, means biasing said cross-slide in a direction effecting control engagement of said follower abutment with said contour cam, a stop abutment between said cross-slide and said main slide to limit the movement of said cross-slide in response to said biasing means upon disengagement of said follower abutment and cam, and means to disengage said follower abutment from said cam during back traverse of said main slide to provide relief for said tool from the work.

22. In a lathe of the class described, a main tool slide adapted to traverse and feed the cutting tool, a support for said slide, a cross-slide mounted on said main slide and carrying the cutting tool, a contour cam carried by said support and disposed adjacent the path of movement of said main slide, a follower abutment on said crossslide adapted to ride in engagement with said contour cam during forward feed of said main slide to control the contour cutting movement of the tool, means biasing said cross-slide in a di rection effecting control engagement of said fol lower abutment with said contour cam, a slide plate on said support and to which said contour cam is secured, said plate being movable in the same direction as said cross-slide, a step cam carried by said support and disposed to be engaged by an abutment on said slide plate in response to said biasing means, and automatic means to index said step cam in relation to said last named abutment to determine the depth of cut for said tool during each successive forward feed of said main slide.

23. In a lathe of the class described, a main tool slide adapted to traverse and feed the cutting tool, a support for said slide, a cross-slide mounted on said main slide and carrying the cutting tool, a contour cam carried by said support and disposed adjacent the path of movement of said main slide, a follower abutment on said crossslide adapted to ride in engagement with said contour cam during forward feed of said main slide to control the contour cutting movement of the tool, means biasing said cross-slide in a direction effecting control engagement of said follower abutment with said contour cam, a slide plate on said support and to which said contour cam is secured, said plate being movable in the same direction as said cross-slide, a step cam carried by said support and disposed to be engaged by an abutment on said slide plate in response to said biasing means, and a pawl and ratchet connection between said step cam and said main slide whereby said step cam is indexed by each back traverse movement of the main slide to adjust the depth of cut for the tool for the next succeeding forward feed of the main slide.

24. In a lathe of the class described, a main tool slide adapted to traverse and feed the cutting tool, a support for said slide, a cross-slide mounted on said main slide and carrying the cutting tool, a contour cam carried by said support and disposed adjacent the path of movement of said main slide, a follower abutment on said cross slide adapted to ride in engagement with said contour cam during forward feed of said main slide to control the contour cutting movement of the tool, means biasing said cross-slide in a direction effecting control engagement of said follower abutment with said contour cam, a slide plate on said support and to which said contour cam is secured, said plate being movable in the same direction as said cross-slide, a step cam carried by said support and disposed to be engaged by an abutment on said slide plate in response to said biasing means, a pawl and ratchet connection between said step cam and said main slide whereby said step cam is indexed by each back traverse movement of the main slide to adjust the depth of cut for the tool for the next succeeding forward feed of the main slide, and automatic power means operable upon the back traverse of said main slide after the final cut of the tool to recock said step cam to starting position for another cycle.

25. In a lathe of the class described, a normally stationary step cam disposed to determine the depth of cut for the tool in repeat cutting operations, and automatic means to index said step cam to present successive steps thereof in operative position in correlation to repeat cutting operations of the tool whereby each step of the cam determines the depth of cut for a corresponding cutting operation.

26. In a lathe of the class described, a normally stationary step cam disposed to determine the depth of cut for the tool in repeat cutting operations, automatic means to index said step cam to present successive steps thereof in operative position in correlation to repeat cutting operations of the tool whereby each step of the cam determines the depth of cut for a corresponding cutting operation, and means to return the step cam to starting position upon completion of the final cut of a cycle.

27. In a lathe of the class described adapted to employ repeat cutting operations upon a Workpiece wherein the cutting tool has to be adjusted for depth of cut for each cutting operation, a step cam having an individual step position for each cutting action to determine the depth of cut for the tool, a control drum having means thereon to determine the automatic traverse and feed of the tool and repeat of cut therefor for each successive cutting operation, and common means to index said step cam and drum between the successive feeding operations for the tool.

28. In a lathe of the class described adapted to employ repeat cutting operations upon a Workpiece wherein the cutting tool has to be adjusted for depth of cut for each cutting operation, a step cam having an individual step position for each cutting action to determine the depth of cut for the tool, a control drum having means thereon to determine the automatic traverse and feed of the tool and repeat of cut therefor for each successive cutting operation, and common means connected to said tool whereby back traverse of the tool indexes both said step cam and said drum for the next succeeding forward traverse and feed for the tool.

29. In a lathe of the class described adapted to employ repeat cutting operations upon a workpiece wherein the cutting tool has to be adjusted for depth of cut for each cutting operation, a step cam having an individual step position for each cutting action to determine the depth of cut for the tool, a control drum having means thereon to determine the automatic traverse and feed of the tool and repeat of cut therefor for each successive cutting operation, means con-- nected to said tool whereby back traverse of the tool indexes both said step cam and said drum for the next succeeding forward traverse and feed for the tool, and means actuated in response to a dog on said drum to effect return of said step cam and drum to start position after completion of the final cutting operation of the tool on a workpiece.

30. In a lathe of the class described adapted to employ repeat cutting operations upon a workpiece wherein the cutting tool has to be adjusted for depth of cut for each cutting operation, a step cam having an individual step position for each cutting action to determine the depth of cut for the tool, a control drum having means thereon to determine the automatic traverse and feed of the tool and repeat of cut therefor for each successive cutting operation, means to index said step cam and drum between the successive feeding operations for the tool, and automatic time delay means actuated by said controls on said drum to produce a dwell between the termination of the feeding of the tool and the start of the back traverse therefor whereby the end of the cut is normal to the axis of rotation of the workpiece.

LORENZ A. LEIFER. CHARLES H. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 689,845 Barrow Dec. 31, 1901 2,370,286 Berger Feb. 27, 1945 FOREIGN PATENTS Number Country Date 580,235 Great Britain Aug. 30, 1946 

